Hello Barry,
The only problem that I can see with this poster is that it seeks to communicate it's message by issuing a negative command to the reader. And it does this without incentive.
Anybody that has kids will know that it is much harder to get them to STOP doing something, than it is to promote a positive response - if you prohibit a particular act it simply grows more attractive. Reward a positive, on the other hand, and the benefits are known to increase exponentially.
In fact, this psychology is just as effective when communicating with adults. The rewards of positive behaviour always motivate more strongly than the threat of punishment. That is why successful companies motivate their workforce with the chance of promotion rather than by threatening pay cuts.
The command made here, to STOP BEING AFRAID, is neither incentivised nor justified within the message itself and is undermined by this ommission.
WHY should we stop being afraid? What do we have to gain?
In other words, you need to offer a better way.
So, in this spirit, I offer the following alternative version of the same message (it is in no way intended to apply solely to the Americans here - insert your own country of birth as necessary):
I WANT YOU TO BE MORE UNDERSTANDING AND APPRECIATIVE OF OTHER AMERICANS,
OF OTHER RELIGIONS,
OF OTHER CLASSES,
OF OTHER NATIONS
AND SPEAK OUT!
YOU'RE AMERICANS FIRST.
ACT LIKE IT!
YOU'LL FEEL MUCH BETTER!If you take this approach, I guarantee you will find a more receptive audience. Of course, you'll never convince those who simply will not be told what to do.